“…A nonclassical potential is the potential whose zero set is an unbounded subset, for example, V(x, y) = \xy\* on R 2 . The nonclassical potentials are studied by Gurarie [8], Levendorskii [9], Robert [11], Simon [13], Solomyak [14], and Tachizawa [15], and they only consider potentials whose zero sets are cones. We will outline the content of this paper.…”